1. Field of the Invention
The present invention relates to a pixel, an organic light emitting display device, and a method for driving an organic light emitting display device using the pixel, and more particularly to a pixel, an organic light emitting display device, and a method for driving an organic light emitting display device using the pixel, using an electric current.
2. Discussion of Related Art
Organic light emitting display devices are a type of flat panel display device that make use of organic light emitting diodes that emit light by re-combination of electrons and holes. The organic light emitting display device has advantages of high response speed and small power consumption.
FIG. 1 is a block diagram of a conventional light emitting display device. With reference to FIG. 1, the conventional light emitting display device includes a display region 30, a scan driver 10, a data driver 20, and a timing controller 50. The display region 30 includes a plurality of pixels 40 formed at crossings of scan lines S1 to Sn and emission control lines E1 to En with data lines D1 to Dm. The scan driver 10 drives the scan lines S1 to Sn. The data driver 20 drives the data lines D1 to Dm. The timing controller 50 controls the scan driver 10 and the data driver 20.
The timing controller 50 generates a data drive control signal DCS and a scan drive control signal SCS according to externally supplied synchronous signals. The data drive control signal DCS generated by the timing controller 50 is provided to the data driver 20, and the scan drive control signal SCS is provided to the scan driver 10. Furthermore, the timing controller 50 provides externally supplied data Data to the data driver 20.
The scan driver 10 generates a scan signal in response to a scan drive control signal SCS from the timing controller 50, and sequentially provides the generated scan signal to the scan lines S1 to Sn. The scan driver 10 generates an emission control signal in response to the scan drive control signal SCS from the timing controller 50, and sequentially provides the generated emission control signal to the emission control lines E1 to En.
The data driver 20 receives the data drive control signal DCS from the timing controller 50. Upon the receipt of the data drive control signal DCS, the data driver 20 generates data signals, and provides the generated data signals to the data lines D1 to Dm. Here, the data driver 20 provides the generated data signal to the data lines D1 to Dm every 1 horizontal period.
The display region 30 receives power from a first power supply ELVDD and a second power supply ELVSS both located outside the display device, and provides them to the pixels 40. Upon the receipt of power from the first power supply ELVDD and the second power supply ELVSS, the pixels 40 control the amount of a current flowing into the second power supply ELVSS from the first power supply ELVDD through a light emitting element corresponding to the data signal, thus generating light corresponding to the data signal.
Namely, in the conventional light emitting display device, each of the pixels 40 generates light of predetermined luminance corresponding to a data signal to display an image. However, the conventional light emitting display device may have difficulty displaying an image of a desired luminance due to variation in electron mobility and non-uniformity between threshold voltages of transistors included in each of the pixels 40. To solve the aforementioned problem, the data signal may be supplied as an electric current. In practice, when the data signal is supplied as an electric current, a uniform image can be displayed at the display region 30 irrespective of variation between the transistors used in each of the pixels.
However, since the electric current supplied as the data current is small, it takes a long time to deliver a charge equivalent to the data signal. For example, assuming that a capacitive load of a data line is 30 pF, it takes several ms to charge the data line by means of a data signal current that may vary from several tens to several hundreds of nA. If considering 1 horizontal period 1H of several tens of μs, the charging time of several ms is not an insignificant length of time.